Studies of offspring of chronic alcoholic women have revealed a pattern of malformation with accompanying brain dysfunction termed fetal alcohol syndrome. Prospective study of a cohort of 500 infants (selected from 1529 consecutive pregnancies) indcates that offspring of heavy social drinkers compared to controls had poorer learning on neonatal operant tasks and poorer habituation, as well as more dysmorphic features suggestive of fetal alcohol syndrome, although some of these findings were confounded with a nicotine/alcohol interaction. Unusual brain findings similar to those found in offspring of chronic alcoholic mothers were also found, although sample size was very small. The purpose of the presnt study is to re-examine the same cohort of 500 infants again at age 4 years to study the effects of heavy social drinking duing pregnancy on cognitive, motor and language development, on growth parameters and morphological development, and on behavior and neuropsychological function.